Interface IExtensionPoint

public interface IExtensionPoint

An extension point declared in a plug-in.
Except for the list of extensions plugged in to it, the information
available for an extension point is obtained from the declaring plug-in's
manifest (plugin.xml) file.

These registry objects are intended for relatively short-term use. Clients that
deal with these objects must be aware that they may become invalid if the
declaring plug-in is updated or uninstalled. If this happens, all methods except
isValid() will throw InvalidRegistryObjectException.
For extension point objects, the most common case is code in a plug-in dealing
with one of the extension points it declares. These extension point objects are
guaranteed to be valid while the plug-in is active. Code in a plug-in that has
declared that it is not dynamic aware (or not declared anything) can also safely
ignore this issue, since the registry would not be modified while it is
active. However, code in a plug-in that declares that it is dynamic aware
must be careful if it access the extension point object of a different plug-in,
because it's at risk if that other plug-in is removed. Similarly,
tools that analyze or display the extension registry are vulnerable.
Client code can pre-test for invalid objects by calling isValid(),
which never throws this exception. However, pre-tests are usually not sufficient
because of the possibility of the extension point object becoming invalid as a
result of a concurrent activity. At-risk clients must treat
InvalidRegistryObjectException as if it were a checked exception.
Also, such clients should probably register a listener with the extension registry
so that they receive notification of any changes to the registry.

Method Detail

getConfigurationElements

Returns all configuration elements from all extensions configured
into this extension point. Returns an empty array if this extension
point has no extensions configured, or none of the extensions
contain configuration elements.

Returns:

the configuration elements for all extension configured
into this extension point

In the past namespace was dictated by the name of the bundle. If bundle org.abc
contributed registry element with Id of MyId, the namespace of
the element was always set to org.abc, producing the qualified name of
org.abc.MyId.

The namespace used to be the same as the bundle name. As a result, the getNamespace()
method was used both to obtain the name of the bundle and to obtain the namespace of a registry
element.

Since 3.2, the extension registry allows elements to specify qualified name. The extension point
of the plug-in org.abc could specify org.zzz.MyExtPoint as
an Id. In this case, namespace name is org.zzz, but the contributor
name is org.abc.

(The use of a simple Id is still a preferred way. Whenever possible, specify only the simple
Id and let runtime take care of the rest.)

If your code used the getNamespace() to obtain the name of the contributing bundle,
use getContributor(). The typical usage pattern here is to find a bundle name to obtain
some information from the corresponding OSGi bundle. For example, deducing the file location
specified as a relative path to the bundle install location would fall into this group.

If your code used the getNamespace() to obtain the namespace of the registry element,
use getNamespaceIdentifier(). Typically, this is the case when code is trying to process
registry elements belonging to some logical group. For example, processing notifications for all
elements belonging to the org.abc namespace would fall into this category.

Returns the namespace for this extension point. This value can be used
in various global facilities to discover this extension point's provider.

getExtension

Returns the extension with the given unique identifier configured into
this extension point, or null if there is no such extension.
Since an extension might not have an identifier, some extensions
can only be found via the getExtensions method.

Parameters:

extensionId - the unique identifier of an extension
(e.g. "com.example.acme.main").

getLabel

When multi-language support is enabled, this method returns a displayable label
for this extension point in the specified locale.
Returns the empty string if no label for this extension point
is specified in the plug-in manifest file.

The locale matching tries to find the best match between available translations and
the requested locale, falling back to a more generic locale ("en") when the specific
locale ("en_US") is not available.

If multi-language support is not enabled, this method is equivalent to the method
getLabel().

Parameters:

locale - the requested locale

Returns:

a displayable string label for this extension point,
possibly the empty string

getSchemaReference

Returns reference to the extension point schema. The schema
reference is returned as a URL path relative to the plug-in
installation URL.
Returns the empty string if no schema for this extension point
is specified in the plug-in manifest file.

getUniqueIdentifier

Returns the unique identifier of this extension point.
This identifier is unique within the plug-in registry, and
is composed of the namespace for this extension point
and this extension point's simple identifier.

Returns:

the unique identifier of the extension point
(e.g. "org.eclipse.core.resources.builders")